Improvement in door-spring



struction.

time @anni i WILLIAM Dinvcrnv, or Le Letters Patent No. 87,095,

BANON, NEW HAMPSHIRE.

dated Februar/ry 23, 1869.

IMPROVEMENT 1N DOOR-SPRING.

The Schedule referred to in these Letters Patent and making part of the same.

To all whom it may concern:

Beit known that I, WILLIAM DUNCAN, of Lebanon, in the county of Grafton, and State ofNew Hampshire, have invented a new and useful Device for Shutting Doors; and I do hereby declare that the following is a full and exact description of the same, 'reference being had to the accompanying drawings, and to the letters of reference marked-thereon.

This invention relates to a simple device for shutting doors, gates, 85e., and consists mainly in the employment of a screw and nut, in connection with a. spring or weight, the arrangement being such that when the door is opened the screw is turned, and the nut thus forced upward against the pressure of the weight or spring; consequently, when the door is left free to cl'ose, the spring or weight, acting upon the nut, causes the screw to revolve and shut the door.

The details of construction and manner of operation will be fully described hereinafter.

In the drawings- Figure l is a perspecti tached to a door.

ve view of my invention lat- Figure 2,4 a side elevation of another form of the invention, with portions 'broken away to show the con- To enable others skilled in the art to make and use my invention, I will proceed to describe fully its construction-and operation. i

A represents a plate, which is provided with the slot a, and ears c a', as shown.'

B represents a shaft, or rod, resting in bearings in the ears a a', which has at its lower end, beneath the bearing, the arm b, which is rigidly secured to it in any suitable manner.

This shaft is also provided, near its lower end, with the screw-threads b, of sharp pitch, and near its upper end with the screw-threads b2, of ordinary pitch.

Upon these latter threads turns the nut B.

C represents a nut, turning upon the 'threads'b as shown.

This nnt is provided with a projection, c, which fits snugly into the slot c.

D represents a coiled spring, which encircles the shaft weights may be used to press against the nut, as is shown in fig. 2. l

The operation'bis as follows: he device having been suitably attached to the casing, in any proper position, the arm b is bent to press lightly against the door, as is shown-in the drawing.

Now, when the door is opened, the arm 11 is ofcourse shaft B, thelatter is caused to revolve more or less in its bearings.

This revolution of the shaft necessarily causes the nut to move in a vertical direction, it being prevented slides in the slot a..

The nut, in moving upward, presses against the spring D, or against the weights resting upon'it.A As soon,therefore, as the door is left free to move, the reaction of the spring, or the pressure of the weights, causes the nut C to descend rapidly, the pitch of the screw being short, to facilitate this movement, by means of which operation the screw B is of course By adjusting the nut B up or down, the spring may be caused to bear more or less strongly upon the nut O.

If weights be used, a greater 0r less number may be employed, at will..

By the general 'construction herein described, a simple and efficient device is obtained, which can be cheaply constructed, and cannot readily get out of order.

the exception of the arm.

Having thus fully ldescribedsmy invention, WhatI claim as new, and desire to secure by Letters Patent, is Y The device described, consisting of the slotted plate A, shaft B, nuts C and B', and springs D, or weights E, the whole being constructed, arranged, and operated as described, for the purpose set forth. i

This specification signed and witnessed, this 4th day of January, 1869. Y

Witnesses: WILLIAM DUN CAN.

E. J. DURANT, Y

B, between the nut C and B. Instead of this spring,

Il?. A. OUSHMAN.

forced backward, and as it is rigidly attached to the from revolving-by means of the projection c, which turned, and its arm is caused forcibly to close the door.

It may be attached to any part of the casing, and, if desired, may be entirely concealed from view, With- 

